Need your help on this issue - when I start my X5 and go from Park into Reverse my parking light flashes constantly after emmiting a tone for 3 seconds from the front sensor only - I nearly reversed into a wall because I didn't hear the back sensors beeps sound at all?? this happens quite a bit and other times when I'm parknig they seem to work fine - perhaps it's an intermitent fault and I was just wondering does anybody else experience the same if not similiar problems with the parking sensors.